Composition, structural, and electrical investigations on DC-magnetron-sputtered TiO2 thin films

Amorphous thin films of titanium dioxide (TiO2) with perfect stoichiometry were deposited onto well-cleaned p-type silicon (p-Si) substrates by using DC magnetron sputtering. The thicknesses of the films were measured using an alpha step profilometer. The composition of the films were analyzed using Auger electron spectroscopy (AES), and the films were found to be stoichiometric (O/Ti = 2.08). From the atomic force microscope (AFM) analysis, the surface morphology, the root-mean-square roughness (Rrms), and the average roughness (Rs) were determined. The influence of post-deposition annealing at 673 and 773 K on the composition and on the structural and the electrical properties was studied. The thicknesses of the films were found to be more or less the same irrespective of the annealing temperature and time. X-ray diffraction (XRD) results revealed the amorphous nature of the as-deposited films while the annealed films were found to be crystalline with a tetragonal symmetry. The lattice constants, the grain size, the microstrain, and the dislocation density of the film were calculated and correlated with the annealing temperature. The capacitance-voltage (C-V) characteristics of the Al/TiO2/Si structure were measured using standard techniques, and the dynamic dielectric constants, the flat-band voltages, and the flat-band capacitances of the as-deposited and the annealed samples were evaluated and reported.